System of variation between sizes or classes of semivertical curvedtube bollers



A. D. PRATT. SYSTEM OF VARIATION BETWEEN SIZES OR CLASSES OF SEMIVERTICAL CURVED UBE BOILERS. APPLICATION FlLED Nov. 13, 1917.

1,363,915. Patented Dec 28,1920.

2 SHEETS-SHEE 2.

r` i INVENTOR.

' AT TRNEYS.

UNITED STATES PATENT OFFICE.

ARTHUR D. PRATT. OF SUMMITy NEW JERSEY, ASSIGNOR TO THE BA BCOCK & WILCOX COMPANY, OF BAYONNE, NEW JEBSEY, A CORPOBATION OF NEW JERSEY.

SYSTEM OF VAItIATION BETWEEN SIZES OR CLASSES OF SEMIVERTICAL CURVED- TUBE BOILERS.

Specificaton of Letters Patent.

Patented Dec. 28, 1920.

Application filed November 13, 1917. Serial NO. 201,848.

TO (IN ll'lIOlN z'mag concern Be It known that I, ARTHUR D. PRATT, a citizen of the United States, residing at Summit, in the County of Union and State' trating four classes following the system of variation of thc present invention; and Fig. 3 a diagrammatic view to illustrate the identity of length of curvature of the tubes of any class.

The general design of the Semi-Vertical curved tube boiler comprises two or more, referably three, transverse steam and water drums, set parallel, and connected to a mud drum by water tubes So curved as to enter the tube sheets radially. The steam' space and the water space of the center drum are interconnected to the corresponding spaces of both the front and rear steam drums by a row or rows of steam and water circulating tubes. The main steam outlet Is placed on the top of the center or rear steam drum.

While adhering to this general design it was found necessary by the original manufacturer of this type of boiler to devise Variations from the first class of boiler offered. At first these variations were necessary to meet specific space conditions, that is, a number of classes of boiler of the type in question were designed to fit into given spaces in existing boiler rooms: later a still further increase in the number of variations was necessary to take care of new types of stokers being introduced and the development and improvement in burning different classes of fuel. This practice has been consistently followed and the variations from the original boiler offered have so increased that one manufacturer has at the present time, not including numerous special classes, 18 standard classes listed. While the same general design of transverse steam and water drums connected by curved tubes was followed in all of these classes, no consideration appears to have been given to a logical variation from the class'orlgnally ofi'ered or between classes later developed. In creating new classes, the relative location of drum centers, which determine the length and inclination of the tubes, appears to have been arbitrarily selected, at first to meet specific space conditions, and later to meet conditions required for the size and form of furnace necessary for a given type of stoker, or required for a given class of fuel. With the drum centers'for a new class of boiler determined on such a basis, and the lengths of tubes thus approximately fixed, for a boiler of a given Width, such Width being determined either by the space conditions or the furnace requirements, the variation in amount of heating surface was obtained by supplying different numbers of tubes per section of boiler Width.

The ultimate result of this practice is partially indicated by Fig. 1 which illustrates compositely the drums and tube outlines of thirteen of the existing eighteen classes listed by one manufacturer of this type of boiler. In but two of the eighteen classes are the tubes of the same length. In all of the classes there are 226 different lengths of long tubes, and the number of such tubes per section varies in the different classes from nine to seventeen. The diameters of both steam and mud drums vary in the different classes,

there being in all four diameters used in seven different combinations. The relative location of drum centers is different inall but three of the classes, and due to this fact the inclination of the different banks of tubes in the Various classes is different. The variation in relative location of drum centers and the difference in drum diameters used necessitates a great variation in the lengths of bend necessary. In the 226 lengths of long tubes used in all'classes approximately 4 40 lengths of bend are necessary.

Reference to Fig. 1 will make clear the illogical method hitherto used in obtaining variation between classes of the Semi-Vertical curved tube design of boiler. One of the classes represented, designed to meet certain conditions of space,'heating surface and furnace form, comprises the steam drums 4, P and 4 of a iven diameter, connected by corresponding anks of tubes 5, 5 and 5 having a given length and inclination, to `a mud drum of the size indicated by the numeral 1. Another class comprises the steam drums 6, 6" and 6 in Which the tubes of the corresponding banks 7, 7 and 7 b are longer than those of the class above referred to and have a different inclination to the mud drum to meet other required conditions. These tubes are connected to a mud drum of the size indicated by the numeral 2. Still another class comprises the steam drums 8, 8'and 8 a mud drum of the size indicated by the numeral 3 and the corresponding connecting banks of tubes 9, 9'* and 9", which are longer than either of those above referred to and have a different inclination to the mud drum. I have merely selected these three classes from the large number shown, as typical, and it will be readily seen that no loglcal method'of variation between classes was followed, but, as above stated, each class was designed to meet a given condition as to space, heating Surface or other factor.

Among the disadvanta es of obtaining variation between classes of this type of boiler, as now practised, may be mentioned the following: absolute lack of Standardization. The completed drums drilled with their tube holes of no two of the eighteen classes are interchangeable. While certain of the classes are alike in drum diameters the relatively different location of drum centers, and the different number of tubes in the different banks means entirely different tube hole drillings. This fact makes it impracticable, from 'a manufacturin standpoint, to make up these drums comp ete except on specific order. 4

The great number of tube lengths necessary to meet the requirements of all classes- 226 different lengths in the case of the manufacturer cited above-means an excessive tube stock to'be carried. The labor involved in the Shop due to the number of lengths of tube bends-approximately 440 in the case of the manufacturer above cited-will also be greatly in excess of that required under a system of variation between classes which would materially reduce such number.

The purpose of the present invention is to l provide a logical System by which variation between sizes or classes of Semi-Vertical curved tube boilers may be obtained by a variation in but one of the features of design of this type of boiler, namely, in the length of the Straight portion of the tube, The proposed system is illustrated in F ig. 2. This figure illustrates four classes or sizes of boiler in which the numeral 10 designates the mud drum common to all classes, while the numerals 11, 11 and ll 12, 12` and 12 13, 13. and 13, and 14 1a and 14 designate the steam drums o the smallest to the largest class respectively. The variation between sizes or classes is obtained by moving the steam drums toward or away from the mud drum in planes aralle] to their respective banks of tubes. lthough I have indicated but four classes it is obvious that the system can be extended indefinitely and, Whatever -the number of classes, the inclination of the different banks of tubes to the mud drum and their respective steam drum will be the same. While Fig. 2 shows five tubes, five tubes and six tubes in the rear, middle and front banks respectively, the system is applicable whatever the number of tubes per bank. While F ig. 2 shows the steam drums of any one class on the same horizontal line, the System is applicable regardless of the relative Vertical location of the steam drums of any one class. Fig. 2 will indicate that the mud drum, 10, as to diameter and tube hole drilling is alike for all classes regardless of the number. Like'- wise the front, center and rear steam drums are alike in diameter, and the tube hole drilling will be such that the front drum may be used as the front drum of any class regardless of the number; the center drum may be used as the center drum for any class regardless of the number, and the rear steam drum may be used as the rear drum of any class regardless of the number. The system permits of the same length of curvature or bend of any individual tube of any of the classes, the only difference in the tubes bein in the length of the straight portion. hat is, the length of curvature or bend, 15, of the upper end, and the bend, 16, 100 of the loWer end of the front tube of the front bank is the' same for that row of tubes for all classes regardless of the number of classes. The same holds true for all of the v other rows of tubes of all the banks, each row having its individual length of curvature or bend, but being the same in the same row of all classes regardless of the number of classes or the number of tubes per bank of any class, the only difference being in the length of the' straight portion of such tubes. This feature of my invention is illustrated in F ig. 3 in Whichthe tubes a and b may be taken to represent the tubes of the first and second rows of the front bank of the smallest size of boiler, that is, the boiler having the steam drums 11, 11 and 11 and the tubes c and (i to represent the first and second rows of the front bank of the next larger size of boiler, that is, the one having steam drums 12, 12 and 12. The length of curvature or bend of the upper ends of these tubes is represented by the angles a', b', o'and d' respectively, it being noted that the angles a' and a' are the same, and the angles b' and d' are the same, and, that the only difference in the corresponding tubes of the two classes is in the length of their straiht portions that is, taking the line S, in ig. 3 as thelength of of the front bank, the increase' in length of the straight portion of the first row of tubes of the front bank of the next larger class ls represented by the line A; and the total len th by the line L.

his rule holds true as to thetubes of corresponding rows Whatever the size of the class, that is, the tubes 15, 17, 18 and 19, all being tubes of the first .row of the front banks of the four classes shown in Fig. 2, have the same curvature or bend at their upper ends, the only difi'erence being in the lengths of their straight portions. Similarly the tubes 20, 21, 22 and 23', being the tubes of the second row of the first bank, have the same curvature or bend at their upper ends, the only difference being in lengths of their straight portions.

\Vhile the system of variation between classes may be eXtended indefinitely, the four classes shown in F ig. 2 will meet practically every requirement of horse power and space conditionsithat may be encountered.

The advantages of my system may be briefiy summarized as follows.

1. The advantages from a manufacturing standpoint are those accompanying any real and logical Standardization.

.2. 'But two diameters of drums are contemplated instead of four as at present used by the manufacturers of this type of boiler, thus reducing the drumplate stock that must be carried.

3. The drums of any class, regardless of the number of classes, would be for a given Width of boiler, interchangeable. With a knowledge of the widths in the greatest demand it would be practicable, in dull times, to make up complete drums for stock, to meet prompt deliveries at rush times, without involving excessive carrying charges.

4. Assuming that the four classes indicated in Fig. 2 would meet practically all of the conditions of installation that will be encountered, a tube stock' for all classes would consist of but 64 lengths as compared with 226 lengths under the System of variation between classes as used by the manufacturer above cited.

5. These 64 lengths of tube Would require but 28 lengths of curvature on bend as against the approximate 440 lengths necessary in present practice.

6. The relative Vertical location of the steam drums would not alect the proposed system.

7 Under the proposed system, any location of steam outlet, any baffle arrangement, any furnace arrangement or any superheater arrangement now in use with the Semi-Vertical, curved tube type of boiler could be usedwithout altering the proposed method of variation between classes.

What I claim and desire to secure by Letters Patent of the United States is 1.`In boilers of the Semi-Vertical curved tube type having upwardly diverging banks of tubes, sets of standard upper transverse drums and a standard lower transverse mud drum, said drums having tube 'holes standardized both as to size and location, in combination with standard interchangeable sets of Water tubes designed to aflord boilers of different sizes, said sets of tubes having straight portions with curved ends arranged to be expanded in the tube holes of the standard drums, the sets differing from each other solely in the length of their straight portions, whereby boilers of different sizes of the same Semi-Vertical curved tube type may be assembled from the same standard drums and sets of tubes of varying length having standard curvatures in their curved end portions.

2. In boilers of the Semi-Vertical curved tube type having upwardly diverging banks of tubes, sets of standard upper transverse drums and a standard lower transverse mud drum, said drums having tube holes standardized both as to size and location, in combination with standard interchangeable sets of water tubes designed to afford boilers of different sizes, said sets of tubes having straight portions with curved ends arranged to be expanded in the tube holes of the standard drums, the sets differing from each other solely in the length of their straight portions, and sets of horizontally extend- 100 ing circulators arranged to Connect some of the drums, said sets of circulators differing in length, but all being adapted to enter the same tube holes of the standard drums, whereby boilers of different sizes of the 105 same Semi-Vertical curved tube type may be assembled from the same standard drums and sets of Semi-Vertical tubes of varying length having standard curvatures in their curved end portions.

3. The method of making boilers of semivertical curved tube type having upwardly divergingbanks of tubes and of different horse power capacities, consisting in eX- panding into sets of upper and lower trans- 115 Verse drums, sets of water tubes having straight portions with curved ends, each of said tubes extending from the lower transverse drum to one of the upper transverse drums, corresponding tubes of the different 120 sets of tubes for boilers of diflerent capacities differing from each other solely in the length of their straight portions between -the curved end portions, and corresponding of the tubes.

4. A series of Semi-Vertical curved tube boilers having upwardly diverging banks of tubes and of progressively increasing capacities, each boiler of the series having a plurality of upper transverse drums and a lower transverse drum With sets of tubes connecting the lower drum With each of the upper drums, each drnm ofeach boiler in the series being identical with all of the corresponding drums of the other boilers of the series and each tube of each boiler of the series having ends identical as to Curvature with all of the corresponding tubes of the other boilers of the Series, the length of the straight portions of corresponding tubes of the Series increasing progressively throughout the Series.

5. In the art of manufacturing water-tube boilers having upwardly diverging banks of. tubes and of different horse power capacities and having a plurality of transverse drums at different levels connected by banks of Water tubes having curved end portions, the method which consists -in preparing a plurality of sets of drums having tube holes of the same size and location, pre# paring a plurality of sets of tubes for different boilers, the sets differing from each other only in length, and constructing therefrom a boiler of a desired capacity by connecting intostandard drums a set of standard tubes as above provided and which are of a length between their curved end portions corresponding to the desired horse power of the boiler; whereby boilers of different horse power capacities may be made up from said parts, said boilers differing from each other solely in the length of the straight portions of the tubes of said banks.

6. In the art of making water-tube boilers having upwardly diverging banks of tubes and of different horse power capacities having a plurality of transverse drums at different levels connected by banks of water tubes having curved ends, the Steps consisting of providing a plurality of sets of drums each alike as to location and size of tube holes, providing a plurality of sets of water tubes, said sets difl'ering solely in the length of their Straight .portlons and each set adapted to be connected'to any set of said drums, and buildinga boiler of any desired horse' power within certain limits by connccting into aset ofsaid drums a set of said Water tubes having a length seleoted in accordance with the boiler horse power desired.

In testimony whereof I have hereunto signed my name in the presence of two subscribing WitnesSes.

ARTHUR D. PRATT. VVitnesses:

JOHN A. W. Dixon, E. L. BRINKERHOFF. 

